Update README

Author: jamieburchell

readme.rst

@@ -1,3 +1,16 @@
+.. ⚠️ WARNING::
+
+   This is a **personal fork of CodeIgniter 3**, maintained **only for my own use and for the company I work for**.
+   It exists to **update CodeIgniter 3 for newer PHP versions** used in our projects.
+
+   - 🛠️ This fork is **not intended for public use**.
+   - ❌ I don’t provide support, accept issues, or review pull requests.
+   - ⏳ Compatibility with older PHP versions is **not guaranteed**.
+   - 🔄 **Version requirements and compatibility may change at any time without notice.**
+   - 🔍 If you’re looking for a maintained public fork, there are **other community versions** available on GitHub.
+
+   Use this repository **at your own risk**.
+
 ###################
 What is CodeIgniter
 ###################